Study On Interaction On 17β-Estradiol And Amide Herbicides With Microcystis Areuginosa

Environmental endocrine disrupters, as emerging pollutants, have been received increasing attention. Steroid estrogens can't be completely removed by traditional water treatment, leading to the residue of 17β-estradial ranging from several ng/L to severalμg/L, such concentrations are high enough to cause endocrine disruption effect to human and wildlife. This work use Microcystis aeruginosa as experimental organism, investigating the impact of E2 to growth rate of M. aeruginosa, and exploring the biodegradation of E2 by algae suspension. The results indicated that at the range of 0.5～4.0 mg/L, E2 slightly stimulates the growth of M. aeruginosa, and exacerbating with the increasing concentrations. On the other hand, M. aeruginosa demonstrated an excellent efficiency to remove E2, and the degradation fit well with first-order kinetics. In the presence of M. aeruginosa, half-life of E2 are approximately 2.0 d, by contrast, it is 39.6 d in the control treatment. Therefore, M. aeruginosa plays an important role on biodegradation of E2, and possesses effective capacity to remove such contaminants.Acylamide herbicides are now the heavily used herbicides worldwide. Most of the herbicides release into atmosphere, water and soil by various ways during the usage, polluting the environment. This work use M. aeruginosa as model organism, studied the toxicity of alachlor, acetochlor and butachlor to M. aeruginosa by investigating the impact of biomass, photosynthesis system and cell group phenomenon. The results indicated that for the biomass, Acylamide herbicides caused little impact to M. aeruginosa. On the later days of experiment, low concentrations of herbicides stimulate the growth of algae and high concentrations inhibit the growth. From the content of chlorophyll a and phycobiliprotein, acylamide herbicides may inhibit their synthesis and damage the photosynthesis system. The destruction exacerbate with the increasing concentration and time. The apparent stimulation effect in low concentrations is not positive, and the increase of biomass may caused by some abnormal cells. Group phenomenon was observed on algae treated by acylamide herbicides, also exacerbating with increasing concentration and time. Algae forms group to resistant environmental pressure and obtain higher survival. Acetochlor displayed a higher toxicity to M. aeruginosa when compared with the results from alachlor.In the experiments of oxidative damage, three acylamide herbicides all caused oxidative pressure to M. aeruginosa, and fat peroxide increased. To keep the balance of formation and elimination of radicals in cells, the reactivity of antioxidant enzyme enhanced. Acechlor has a higher impact on the content of MDA, SOD and POD in M. aeruginosa, further demonstrated the higher toxicity of acechlor to alachlor.